Nmap (Network Mapper) is a security scanner originally written by Gordon Lyon (also known by his pseudonym Fyodor Vaskovich) used to discover hosts and services on a computer network, thus creating a "map" of the network.

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How best to enumerate a server network

What techniques do you typically use, when you start a gig at a complex environment and no one can tell you what servers are out there, and documentation doesn't exist? I typically start off with ...
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How do I test my firewall rules?

I've setup some rules in ufw and I've turned it on. Now I want to ensure my rules actually block traffic. However, when running nmap -PN -p <my_port> <ip> from my local workstation it ...
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35 views

Nmap external scan shows port open, ASA says port is not open, but do get an socket

Folks, have a weird one, need your expert help. For one of our heavily used external facing server which came up in an audit, nmap -Pn scan shows the following: Starting Nmap 5.51 ... Host ...
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667 views

nmap and arp-scan inconsistent IP-MAC results

I seem to get variable and inconsistent results for the IP/MAC addresses from a particular machine, using nmap or arp-scan. The machine has 3 interfaces, and this is what it shows: $ uname -a Linux ...
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69 views

ACL Rule to Open UDP Ports

I have the current rules in an attempt to open port 5060 and 10000-20000 for my VoIP provider. We are on a Cisco 1921 router. This ACL is applied to the WAN port on the router facing the ISP. Nmap ...
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94 views

How to reverse arp using nping for Windows

I would like to send a reverse ARP to resolve an IP address given a MAC address using nping for Windows. The documentation is not clear on how this should work and I'm unable to find any examples ...
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102 views

Network audit tracker

I'm looking for a tool like PBNJ (http://pbnj.sourceforge.net/) but not quite. The functionality I'm looking for is something I can throw into cron to run daily or weekly, scan a network(s), store the ...
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Issue with Netgear GS108T Managed Switch and Jumbo Frames

I recently purchased a Netgear GS108T managed switch and I am trying to configure jumbo packets between my NAS (Thecus N4100Pro), PC and managed switch. I should mention the fact that I was able to ...
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One device shows down when more than 160 ip addresses are scanned with nmap

This is bugging me. I consistently have a single device that fails to respond to an nmap scan when more than ~160 IP addresses are specified. I seem to get mixed results between 150-160 IP addresses ...
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146 views

Why does scanlogd miss port scans?

I am running scanlogd to detect port scans. I have observed the following to generate a log message in /var/log/syslog. When I use zenmap (nmap gui) to port scan this system from another computer on ...
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Nmap SYN Scan blocks all connections?

I have ServerA (running Ubuntu 12.04 (IP: 10.10.10.200)), a KVM DomU of an also Ubuntu Dom0 that is trying to perform a scan against ServerB-ServerZ (Mixed OS (IPs:10.10.10.20-199)) using the command: ...
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nmap port scan for vpn and proxies

I am trying to detect the vpn and proxies from the iplist so is anyone know the fastest and reliable scan command for nmap? right now I am using this nmap -sS -sU -T4 -A -v -PE -PP ...
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Unknown device showing up in network scan

I need some help finding a device that has been showing up whenever I scan my network using Spiceworks' "Inventory" scan. I can ping the device, but nslookup returns a non-existent domain, and ...
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27 views

Find any/first alive host in subnet

I'm trying to find a quick way to check if there are ANY alive hosts in an IP range by pinging them. eg: i don't need to know what hosts are alive, just if one or more is responding to a ping. This ...
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outlook doing remote portscanning

A while ago I switched my mailbox on another domain and configured outlook with an exchange server on that domain. Recently for some strange reason my hosting provider has been complaining that ...